The investigation into an inferno at the home of a missing millionaire and his family officially became a murder hunt yesterday after one of the bodies found in the charred wreckage of the mansion was identified as the businessman's wife.

Jill Foster, 49, was shot in the head before the family home in the idyllic Shropshire village of Maesbrook was set ablaze in the early hours of Tuesday morning.

A second body discovered among the remains of Osbaston House, a rambling £1.2m country pile, has yet to be identified but police said it was that of an adult male, They are seeking to confirm it is Christopher Foster, although an all-ports alert remains in force in case he is trying to flee the country. "Tests are needed to establish a cause of death for the body," said Superintendent Gary Higgins, of West Mercia Constabulary.

The house had been barricaded from the inside and a horse box with flat tyres parked across the property's drive to prevent emergency services reaching the scene.

Investigators have yet to trace the couple's 15-year-old daughter, Kirstie, a pupil at Ellesmere College. Her three show ponies were found shot dead alongside three dogs in the family's stables, situated in the 15-acre grounds. She was chatting with friends on the Bebo networking website until 1am on Tuesday when she was cut off suddenly, four hours before neighbours heard explosions coming from the house.

A fourth dog was found lying close to the dead couple. A .22 rifle recovered from the scene was identified as belonging to 50-year-old Mr Foster. Spent and unspent cartridges were scattered around the bodies. However, police could not confirm whether it was the murder weapon and further tests are under way.

With continuing safety concerns over the fire-devastated building, and so much debris spread over a large area, it could take several days or even weeks before forensic science teams finish the task of sifting through the premises.

Search teams were forced to withdraw from the main part of the house over the weekend as the walls began to lean in towards where officers were working.

Detective Superintendent Jon Groves, of West Mercia's major investigation unit, who is leading the inquiry, said it was still far from clear what had happened before the blaze. "Although this is now being treated as a murder, we are keeping an open mind as to the circumstances leading up to the incident," he said. "There has been a lot of speculation in some sections of the media, which is not helpful."

One report suggested that Mr Foster had fled the country. Another alleged that he had recently turned his home into a "fortress" after learning of a kidnap plot against his daughter.

Meanwhile, a businessman who was cleared of blackmailing Mr Foster two years ago in connection with a failed land deal in Cyprus said he had been offered £50,000 to murder his former associate.

Leo Dennis, 43, a former bouncer, said he had also been approached by the millionaire to act as his personal bodyguard: "Chris was surrounded by a lot of shady people. He wanted me to protect him, but I refused the job offer because I thought things were going too far, especially with people talking about what amounted to murder."

Mr Foster was in deep financial trouble by the time fire engulfed his home: bailiffs arrived at the 400-year-old property even as fire crews struggled to bring the blaze under control. But, despite the tensions, the family were keeping up appearances of normality, even attending a neighbour's barbecue in the affluent village hours before the murder.

The businessman, who had been ordered by liquidators not to sell his home, faced legal action following the collapse of his technology company Ulva Ltd, which owed £800,000 in tax and up to £1m to suppliers. A High Court judge found he had stripped the failing company of its assets, transferring them to a new firm he had established. The judge said Mr Foster "was not to be trusted", adding that he was "bereft of the basic instincts of commercial morality".

Terence Baines, a former director of Mr Foster's company Ulva Ltd – of which Mrs Foster was company secretary – said it was possible Mr Foster had "just flipped because the pressure of it was too much for him".

Prayers were said for the family at the local St John's church yesterday. The Rev David Austerberry said: "The events which have unfolded in our village this week have bewildered and stunned every one of us, not only in this community but across the country. It is hard to grasp exactly what has happened and it is clearly going to be some time before everything is revealed but today we pray for the Fosters and their family."